This paper aims to extract the common denominator of the architectural characteristics in Tadao Ando’s museums to derive his background philosophy. Despite different places, sizes, and programs, the common denominator of architectural characteristics can be summarized as follows: First, the access to the museum is accompanied by water and is intended to climb along a deliberately detoured approach. Visitors take a slow walk on the ascending path and get out of their daily routine. Second, the path that descends immediately after entering the museum prepares the mindset necessary for appreciating the exhibits after taking a walk outside. This ascending, descending, and detouring means that his museums are far from convenience ideology pursuing the shortest path. Third, to harmoniously distinguish between nature and humans, his museum, composed of simple geometry, transcended the obsession with the main façade, but the orientation toward the main entrance is clear. Fourth, the entrance hall of his museum acts as a boundary point between the interior and exterior. Functional space and emotional space are combined for the exhibition where the determined space and the undetermined space intersect and exposed concrete gives consistency to the continuous space.